Osteoarthritis (OA) is the most common musculoskeletal disease with an expected further increase in prevalence due to population aging. Although many drug targets have been identified and preclinical studies have shown efficacy in reducing disease severity, clinical trials on disease modifying OA drugs have failed. Experimental approaches such as testing disease-related differences in expression patterns of selected genes or proteins and analyzing function of these molecules in preclinical models has yielded a large number of pathways and molecules that are abnormally expressed or activated in OA. The limitations of these approaches are (i) that they provide only a selective and biased view of molecular changes that occur in OA and (ii) there has been no successful effort in integrating these findings into networks and prioritizing targets by their relevance as drivers of the OA process. This project leverages (i) our access to and expertise in working with human knee tissues from donors across the entire adult age spectrum and at all stages of OA development; (ii) human knee tissue libraries; (iii) technical advances in large scale, genome wide analyses of transcriptomes and epigenetic changes, which provide the opportunity to generate an unbiased and comprehensive view of the genetic landscape of cartilage homeostasis, aging and OA; (iv) our novel pipeline for integrative network analysis of multi-Omics data sets. Our hypothesis is that the gene expression and epigenetic (miRNA, other non-coding RNA, DNA methylation) data will generate novel signatures, pathways and key regulators of cartilage homeostasis, aging and OA. Aim 1. Healthy cartilage aging: Identify novel transcriptomic and epigenomic (non-coding RNA and DNA methylation) markers of cartilage homeostasis and healthy aging. Aim 2. OA-related changes: Reveal pathways and networks that are disrupted in OA and identify principal regulators of OA pathogenesis. Aim 3. Validation: Confirm differences in gene and protein expression and analyze regulation and function of principal drivers of OA pathogenesis. Impact: To our knowledge, this is the first project to examine genome-wide mRNA expression profiles and genome-wide regulators of expression (miRs, other non-coding RNAs, DNA methylation) in cross-sectional healthy knee aging and OA. The proposed study has potential to lead to the discovery of (i) new biomarkers; (ii) novel pathways and principal molecular switches as therapeutic targets; and (iii) subsets of patients with unique epigenetic signatures and gene expression patterns, resulting in a personalized treatment approach. Ultimately this may lead to interventions to slow aging, and to the identification of therapeutic targets to delay or treat OA. By making the original data sets publicy available, the project will also generate a resource for the scientific community.